1. Field of Invention
The invention relates in general, to firearms, and more particularly to barrel nut designs which ease installation of the barrel to the front end of the upper receiver and which offer structural features that improve the function of the associated gas operated firearm.
2. Description of the Related Art
Firearms in the M16 family, which include but are not limited to, the AR10, SR25, AR15, and piston driven systems and other similar designs, have been in use with military, police, and civilian shooters for nearly 50 years. The M16 family of firearms includes a lower receiver having a stock coupled to the rear end which is connected to an upper receiver having a barrel coupled to the front end. The chamber end of the barrel is received by a portion of the upper receiver and threadedly secured in place. The threads of the upper receiver which receive the barrel nut are not timed in any way but require a minimum torque of 30 foot pounds to secure the barrel in place. The outer surface of the barrel nut has a series of spokes, with gaps formed between, which are used to apply torque to the barrel nut. In order to properly install the gas operating system of the firearm, a gap in the spokes must be in alignment with an opening in the front of the upper receiver. This alignment is required because the gap between the spokes facilitates the entry of either a piston or a gas tube, of the gas operating system, into the interior of the upper receiver. To achieve this required alignment, the barrel nut is often either under- or over-torqued. Both of these conditions present a variety of potential problems which include, but are not limited to, damage to the firearm, poor accuracy during normal operation or compromised operational reliability.
Indirect gas operated M16 type rifles, often referred to as piston driven, such as the design described in U.S. Pat. No. 7,461,581 (“the '581 patent”), are becoming increasingly popular within both the commercial and military markets due to the increased operational reliability offered by such systems. The vast majority of these new piston driven designs rely on the prior art barrel nut common to the M16 family of firearms and as such have inherited the flaws of this design. In addition to the trouble which can result from improper torque being applied to the barrel nut, these piston designs depend on a moving piston, which is supported by the spokes of the barrel nut, to operate. However, the spokes of the barrel nut were not designed for this purpose and, as a result, present a weak point in the operational reliability of these new piston driven designs. Over time some systems which rely on the prior art barrel nut fail because the spokes which support the piston directly, or a removable bushing which houses the piston, start to bend or break, rendering the firearm inoperable. Therefore a need exists for a barrel nut design that will remedy the foregoing and other deficiencies inherent in the prior art.